1. Field of the Invention
The present invention relates to improvements in an automatic air conditioner for a vehicle.
2. Description of the Prior Art
It is well known that an automatic air conditioner has a function of a cooling down control in which the cooling down control means quickly cools down the air without reheating the air while a variable displacement refrigerant compressor is operated in a high capacity mode at a time just after an ignition switch is turned on in a summer daytime. Such an air conditioner is disclosed, for example, in Japanese Patent Provisional Publication No. 1-254418. The air conditioner is of a type in which the compartment temperature is controlled in accordance with the preset target compartment temperature. Therefore, after the compartment temperature has been lower than a predetermined value by the quick cooling down control, the compressor is controlled so that the compartment temperature is adjusted at the preset target compartment temperature.
In heating, the air conditioner is operated in a warm-up control in which an air flow rate by a blower fan and a reheated amount by a heater unit are set at maximum. After the compartment temperature has been higher than a predetermined value by the warm-up control, the reheated amount of the air is controlled so that the compartment temperature is adjusted at the preset target compartment temperature.
Furthermore, when a temperature of engine cooling water is lower than a predetermined temperature, a low water-temperature drive control is carried out in a manner that the air flow rate by the blower fan is adjusted to be lower than a predetermined value or equal to zero, until a predetermined condition is satisfied, for example, until the temperature of engine cooling water acting as a heat source in heating becomes higher than a predetermined value. After such control, the air flow rate by the blower fan is controlled so that the compartment temperature is adjusted at the preset target compartment temperature.
Such an air conditioning system faces a case in which the preset target compartment temperature is changed into a relatively low temperature in operation of the cooling down control by a passenger who intends to more quickly get a cooled compartment although the cooling speed is not accelerated by such a changing of the preset target compartment temperature.
However, when the preset target compartment temperature is set at a relatively low temperature in operation of the cooling down control, the air conditioner system operates to further cool the compartment after the cooling down control so that the compartment temperature becomes a relatively low set temperature. Accordingly, it is necessary to reset the set temperature to get an adequate temperature condition after the cooling down control, thereby losing an advantage of the auto control.
Similarly, in the warm-up control or low water-temperature drive control, it may cause a similar problem when the compartment is over warmed, thereby losing an advantage of the auto control.